A problem with many engineering polymers such as, for example, thermoplastic polyamides is poor weatherability; if the polymers contain aromatic moieties, then sunlight in the ultraviolet region of the spectrum is absorbed, resulting in photodegradation of the polymers. Evidence of this photodegradation includes discoloration and embrittlement of the polymers.
Ridgway, J. Polym. Sci. Polym. Letts. Ed., 13, 87 (1975); Ridgway, J. Applied Polym. Sci., 18, 1517 (1974); Prince, et al, J. Polym. Sci.: Part A-1, 10, 465 (1972), and Bell, et al, J. Polym. Sci.: Part A, 3, 19 (1965) mention polyamides made from a dicarboxylic acid and a single isomer or a binary mixture of geometric isomers of cyclohexanebis(methylamine). Patent documents FR 2189448 (19730528); DE 2263929 (19721229); DE 2225938 (19720527); DE 2060702 (19701210); DE 2060701 (19701210) mention polyamides made from a dicarboxylic acid and a binary mixture of positional isomers of cyclohexanebis(methylamine), i.e., a mixture of trans-1,3- and trans-1,4-cyclohexanebis(methylamine).
EP146717(B1) mentions the preparation of a polyamide from dodecanedioic acid and 4,4′-methylenebis(phenyl isocyanate).
There is a need in the polymer art for improved weatherability characteristics in engineering polyamides and especially for an engineering thermoplastic polyamide that would be transparent, weatherable, and tough. In addition, solvent resistance, typically imparted by semicrystallinity of the polymer is a desired property.